The present invention concerns a heatable rear view mirror. It is in common knowledge to construct rear view mirrors for motor vehicles and especially in the present case, outside rear view mirrors, in such a manner that they may be heated. In this way, condensate, frost, snow ice or the like are removed from the mirror surface by means of a heating element in order that the mirror may provide an unobstructed field of view to the rear. The heating elements are designed, in this case, in the form of surface heating elements, which cover, essentially, the total, full surface of the mirror pane and extend themselves to the back side. Further, it is known, in the case of heatable rear view mirrors, to activate the heating element by means of a thermostat, that is, quasi-automatically, wherein, at a specified outside temperature, the thermo-switch closes the energized circuit to the heating element, so that it becomes activated.
Since the on and off switching of the mirror heating or of the heating element by means of the thermostat is done automatically, the driver of one of these vehicles equipped with one or more such mirrors has difficulties in recognizing whether the heating of the mirror is already automatically switched on or not. Often the mirror pane, for instance, is xe2x80x9cblindxe2x80x9d because of fogging or the like, yet the thermostat has still not switched itself on, since the temperature is not yet low enough, or the thermostat has directly switched to the on position before the driver checks the mirror viewing conditions. However, in the latter situation during the short time since the moment of switching on, no result is noticeable, since the mirror pane is not yet sufficiently warm. In such cases, the mirror heating is often turned on by the driver manually, but this additional manipulation by the driver is often unnecessary. If the thermostat has energized only immediately before the driver check of the mirror viewing conditions, and yet no evidence was seen thereof, then the mirror pane may not yet be sufficiently warmed. In other words, it would be desirable for the driver of a motor vehicle, which is equipped with one or more heatable rear view mirrors, to always know whether in the case of a fogged or xe2x80x9cblindxe2x80x9d mirror, that the automatic heating for the mirror for the elimination of this fogging is already turned on or not. If not, then in case of need, it would be possible to turn on the heater element by a separate switch which parallels the thermostat.
From these considerations, the present invention assumes the purpose to create a possible method for notifying the driver that the automatic mirror heating has been put into operation by the thermostat, whereby, this notification is carried out, so that the driver is not diverted from attention to street traffic.
For the achievement of this purpose, the present invention proposes a heatable rear view mirror, especially for motor vehicles, with at least one mirror pane contained in a mirror housing and at least one heating element dedicated to that mirror pane. The heating element is in the form of a surface heating element, which is actuated by means of a thermostat. This commonly known, heatable rear view mirror is, in accord with the invention, improved in such a manner that, in the case of an activated heating element, at least one display element is also activated, which is visible in a direct front view of the mirror.
With one glance at the rear view mirror, which practically every driver of the motor vehicle makes before, or immediately after starting a trip, in order to check the condition and adjustment of the mirror, the driver can thus verify whether or not the automatic mirror heating or heater equipment is switched on or off. If the visible display element seen in the direct front view of the mirror is activated, the display means that the thermostat has switched on the heating element and the mirror is already heated. In the case of a mirror which is still fogged or xe2x80x9cblindxe2x80x9d, the display indicates to the driver that he need not, on his own, activate the mirror heating from the instrument board, but that the mirror heating is already active, and within a short time, an unobstructed field of vision will appear through the then clear mirror. On the other hand, if the driver recognizes that the mirror is fogged, or is otherwise xe2x80x9cblindxe2x80x9d, and the mirror heating is still not activated, (since the display element is likewise not activated), he can directly activate the mirror heating by means of a corresponding manual switch operation.
Since the display element is visible in direct front view of the mirror the driver is not required to monitor any pilot light or the like on the instrument board. With a short side glance, without even moving his head, he can verify not only the condition of the mirror (adjustment and image quality) but also the on or off situation of the mirror heating. Distraction from attention to traffic is thus minimized.
Preferably, the display element emits light in the visible range, whereby the display element is designed as a light emitting diode (LED). LEDs are available in various colors, withstand on/off procedures in the area of several hundred thousand switching cycles, are insensitive to vibration, require no high connection costs and are easy to install.
In this case, the display element can be placed, for instance, behind the mirror pane and emit through the mirror pane. The display element or the LED lies thus behind the mirror pane and emits through the reflective coating directly in an outward direction. Because of the light penetration through the reflective coating from behind, there arises a certain weakening of the light emanating from the mirror surface. On this account, it is preferred, at the point where the display element will be placed, to remove, at least partially, the reflective layer in dashed lines or punctuations in order to achieve a greater emission of light. Also at this location of the display element, if the heating element is designed as a surface heater, an area must be cut out in the form of a round or rectangular shape. An advantage of the placement of the display element behind the mirror pane is that the display element is encapsulated on all sides by the mirror housing and mirror pane, and thereby protected. Furthermore, the display element lies directly in the sighting field of the driver.
As an alternative to the placement behind the mirror pane the display element can also be located beside the mirror pane in a designed rim area located between the mirror pane and the mirror housing. This placement has the special advantage that, in the case of a massively encrusted mirror pane (thick frost), the display element is more visible, than when it is behind the mirror pane and covered by the massive encrustation.
In a preferred arrangement, the display element and the thermostat are combined into one component and can thus be mounted quickly as one unit, wherein especially wiring costs are reduced.
Just as well, the display element and the thermostat can serve as separate items and then be brought together in a subassembly. This combination process is particularly advantageous in that it is made by a plug-in arrangement.
The brightness of the display element can be advantageously adjustable, in order to make sure that the display is sufficiently bright in a bright surrounding, such as during the day. In a darker situation, that is at night, it must not be so bright that it negatively affects the driver""s vision.
In this matter, the brightness can be automatically controlled dependent upon the intensity of the ambient light and, for instance, the monitor could be a photocell.
The display element, in accord with the basic idea or embodiment of the present invention, can be the display, per se, for the mirror heating. Just as well, however, the display element can illuminate from behind a corresponding symbol which then makes explicitly clear, unmistakably to the driver, that the mirror heating is activated. This symbol can be, for instance, adhesively fastened to the outside mirror surface or it can be engraved in the outside mirror surface or etched therein.
Further details, aspects, and advantages of the present invention arise from the following to be understood as a purely illustrative and non-limiting description of an embodiment in the drawing.